Colo.’s wolverine may get an endangered title

Decision to be announced Jan. 18 for 250 animals in lower 48 states

While state biologists wait for federal authorities to declare a second species – wolverines – endangered by climate change, one lone male wolverine is making the case that Colorado mountains are a critical refuge.

But the wolverine, M56, arrived on his own, and it likely would take an act of the state General Assembly to import any others.

Now entering a fourth winter after trekking from Wyoming across the Red Desert into Rocky Mountain National Park, M56 has not only survived but thrived. Food apparently hasn’t been a problem – marmots in summer, meaty elk bones during winter. State tracking data from a cigar-size transmitter in his belly show M56 roving as far as 100 miles – from forests west of Fort Collins across Interstate 70 to Mosquito Range mountains southeast of Leadville.

Biologists say M56’s exploits have demonstrated that wolverines can climb down from tundra and slink through human territory undetected when necessary, dealing with roads, and probably would not attack cattle.

One day last April, nature photographer Cameron Miller heard a thrashing ruckus beneath the Sawtooth ridge on Mount Bierstadt and thought a large bear was approaching. M56 then emerged silently. “When I saw it,” Miller said, “I wasn’t scared at all. It looked curious.”

Like polar bears, wolverines are directly imperiled by climate change. Only 250 are known to exist in the lower 48 states. They typically weigh around 30 pounds – the size of cocker spaniels, though fiercer. The U.S. Fish and Wildlife Service calculates that 63 percent of habitat suitable for wolverines will vanish by 2085.

For wolverines, vanishing high-mountain habitat with enough late-season snow is the problem. Wolverines “have to choose dens in February that can hold snow until May,” said Bridget Fahey, regional chief of endangered species for the federal government.

A new Wildlife Conservation Society study finds that wolverines also need snow to cache food in “structured chambers” that serve as refrigerators. They crave the coldest, rockiest, steepest terrain they can find, relying on claws that can carry them straight up cliffs.

The listing decision that the government is poised to make could compel action to prevent extinction.

Federal officials could decide that protection is not warranted, but they’re expected to propose a species-recovery plan including designation of critical habitat. The potential snowy bastions for wolverines include the mountains of Montana, Idaho and Wyoming, the Sierra Nevada in California and the southern Rockies in Colorado. Colorado mountains, according to some climate models, could be the last resilient snow zones.

Wolverines historically lived here, but until M56 arrived in the spring of 2009, none had been seen since 1919.

Colorado wildlife commissioners responded a couple of years ago by directing staff members to explore the feasibility of re-introducing about 30 wolverines – as state biologists did with lynx. Wolverines would not solve the state’s problem of needing predators but, unlike wolves or grizzlies, are seen as relatively easy to reintroduce on native terrain.

However, Colorado Parks and Wildlife officials, unable to forge consensus among “stakeholders,” which include the mining, logging and ski industries, dropped the project a year ago. State officials waited to take their cue from the feds.

They declined to discuss the issue publicly, saying to do so could prejudice a delicate political process.

The U.S. Fish and Wildlife Service will announce a decision Jan. 18, and M56’s experience means wolverines “certainly can survive” in Colorado, said Shawn Sartorius, the biologist who is conducting the federal agency’s wolverine status review.

Colorado “looks promising” for wolverines, Sartorius said. “It does not look like wolverines are particularly sensitive to human activities.” Wolverine habitat in the northern Rockies overlaps Idaho ski slopes, and there has been no conflict as wolverines move around.”

I don’t think – whether we list it or not – the ski areas’ activities are going to be changed much,” Sartorius said. Ski areas “are a small impact on the landscape compared to the areas these animals use.”